Cache Memory

Question

Consider the following statements:
S₁ : If capacity misses are most common then the designer should increase the cache associatively, in order to provide more flexibility when collision occurs.
S₂ : To hold the inclusion, lower level cache will be write through.
Which of the statements are correct?

Answer 1

S1 : False

If capacity misses are most common then the designer should increase the cache size.

if conflict misses are most common then the designer should increase the cache associativity.

S2 : True 

When there are multiple levels of cache to hold inclusion(lower level data is the subset of higher level data) we should use Write through policy.

otherwise, inclusion property fails.

Comments

Why we can't use WRITE BACK policy in lower level cache ???

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let us say there are two levels of cache L1 and L2

L1 is subset of L2  (inclusion property)

now if we change some data in L1 and if we use write back policy

then updated data will be present in L1  but that doesn't reflect in L2 (we update data in L2  and main memory when there is a need of replacement)

till then L1 is not subset of L2

which is a violation of inclusion property.

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Got it...Thanks